Milliamp is gracious enough to offer free petalobe screwdrivers to let you tinker away on your iPhone 4. Apple switched away from using regular Phillips screws on the iPhone 4 and now ships iPhone 4s with the new and very tiny 5-star pentalobe screws. The blue pentalobe screwdriver above is the one you're going to get for free, shipping will cost you just $3, not bad considering this exact screwdriver goes for more on eBay.